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ULN2803 Series Datasheet

ULN2803

Octal Darlington Transistor Array

ULN2803 is an eight-way NPN Darlington connected transistor array series. It is especially suitable for the interface between low logic level digital circuits (such as TTL, CMOS or PMOS/NMOS) and higher current/voltage requirements. It is widely used in computers and industrial applications. And consumer products in lamps, relays, printing hammers or other similar loads. All devices have open collector output and freewheeling clamp diodes to suppress jumps.

ULN2803 Data sheet.pdf

ULN2803 Pin Configuration and Function

Pin Number	Pin Name	Description
1,2	SOURCE	Power MOSFET source and circuit ground reference.
3	FB	Feedback input. The useful voltage range extends from 0 V to 1 V, and defines the peak drain MOSFET current. The current limitation, which corresponds to the maximum drain current, is obtained for a FB pin shorted to the SOURCE pin.
4	VDD	Power supply of the control circuits. Also provides a charging current during start up thanks to a high voltage current source connected to the drain. For this purpose, an hysteresis comparator monitors the VDD voltage and provides two thresholds: - VDDon: Voltage value (typically 14.5 V) at which the device starts switching and turns off the start up current source. - VDDoff: Voltage value (typically 8 V) at which the device stops switching and turns on the start up current source.
5,6,7,8	DRAIN	Power MOSFET drain. Also used by the internal high voltage current source during start up phase for charging the external VDD capacitor.